Home Ranges of Male Cerceris Simplex Macrosticta (Hymenoptera, Sphecidae)

or do they remain in one location for substantial periods of time? If they show an attachment to a particular site, do they defend the area or do they share it with other males? We addressed these questions for one species by studying males of Cerceris simplex macrosticta Viereck and Cockerell at two separate sites along State Line Rd., km west of Rodeo., New Mexico. Study area consisted of a strip of roadside ditch, 75 m X 2 m, covered with a dense stand of flowering milkweeds (Asclepias subverticillata). Two mesquites and a sprawling multiflora rosebush were the only large plants at this location. Study site 2, located several hundred meters from study site I, was an area roughly 25 m X o m in an uncultivated pear orchard overrun with clumps of Russian thistle (Salsola kali) and dotted with scattered flowering weeds. From 23-27 July 974 sixteen males were captured in these two areas and marked on the dorsum of the thorax with acrylic paints, each individual receiving a distinctive color or color combination. One or more censuses were made at the two sites on all days from 23 July to 8 August with the exception of 2, 4, and 7 August.

tions about this general pattern of male behavior remain. For example, do flower-visiting males move randomly from area to area or do they remain in one location for substantial periods of time? If they show an attachment to a particular site, do they defend the area or do they share it with other males?
We addressed these questions for one species by studying males of Cerceris simplex macrosticta Viereck and Cockerell at two separate sites along State Line Rd., km west of Rodeo., New Mexico.
Study area consisted of a strip of roadside ditch, 75 m X 2 m, covered with a dense stand of flowering milkweeds (Asclepias subverticillata). Two mesquites and a sprawling multiflora rosebush were the only large plants at this location. Study site 2, located several hundred meters from study site I, was an area roughly 25 m X o m in an uncultivated pear orchard overrun with clumps of Russian thistle (Salsola kali) and dotted with scattered flowering weeds. From 23-27 July 974 sixteen males were captured in these two areas and marked on the dorsum of the thorax with acrylic paints, each individual receiving a distinctive color or color combination.
One or more censuses were made at the two sites on all days from 23 July to 8 August with the exception of 2, 4, and 7 August. RESULTS Home ranges of C. simplex Nine of the marked males were seen again at or near the location where they had been originally captured and seven of the sixteen males were followed for a week or more (Table ). The  The resident males were repeatedly observed pursuing regular circuits between o839-I23o hrs. and rarely as late as I4oo M.S.T. Wasp "yellow" had the smallest circuit of the males we studied and required a mean of 32 sec to complete one flight about its home range (N 9 range, 22-68 sec; 28 July, o82o-I 5). Most of a male's time was spent in flight, although the wasps regularly alighted on perches in their cruising area (Fig. 2). For example, "white" landed on one branch of a rose bush 6 times in 35 minutes (23 July) remained perched an average of 6:5 sec (range, I-9 sec).
Several males had a primary perch to which they commonly returned as well as several secondary perches that were used less frequently. Males pursued any medium-sized flying insect including a wide variety of wasps, beeflies, and brilliant black and red hemipterans as well as male and female conspecifics. Males made physical contact only with conspecific females. The indiscriminate nature of the pursuit flight and the absence of grappling or contact between males leads us to believe that male C. simplex lack behavior designed to defend a territory. The great overlap in routes travelled by different males (at least four males regularly entered "blue's" circuit and easily that many were present in "white's" area) further suggests that males of this species occupy home ranges and not territories.

Attempted matings
Despite many hours of observation, attempted copulations were seen only three times (at o915, o925, Io3o), all in the orchard. In one case a female cruised slowly through a 8alsola clump occa-53o Psyche [September-December Fig. 1. The overlapping home ranges of three males at the orchard study area. "Blue's" home range is outlined with a dashed llne; "red's" home range is outlined with a dot-dashed line; "white-dot's" home range .s outlined ith a solid lne. The circular stippled areas represent prominent Salsola bushes. One large flowering weed is shown schematically in the lower left hand corner of "blue's" home range.
sionally alighting and walking up stems apparently searching for prey, the tenebrionid beetle Metaoloba ruinosa (Alcock, I974), which were sometimes seen in this plant. As she flew slowly past a perched male he flew up and cruised behind her. The female alighted and the male quickly dropped onto her back acing in the same direction as his potential mate. While strokin her antennae with his Ne male held the female's wings out at right angles to her body by sandwiching each wing between his foreand midlegs, presumably making escape more diNcult for the female. His hindlegs grasped the female's abdomen. After several minutes of unsuccessful attempts to copulate, the male released his partner and both flew away. The other two attempted matings also ollowed this general pattern. One took place in a Sabola plant, the other on a flower head of a weed.
The related wasp C. rontata also mates at flowers, initiMly adopting the position used by C. implex (pers. obs.) with the male dismountin after coupling is achieved (Scullen, I965). In the late a1:ternoon, especially be1:ore impending storms, males were seen flying slowly along the large rose bush. The wasps eventually alighted and walked under groups o1: tightly packed leaves and, in one case, into a tube 1:ormed by a rolled leaf, evidently in search ot: a sheltered sleeping site. One male ("red") that had been marked on the morning o1:27 July at a spot 5o m to the south o1: the rose bush was found by this plant at 6Io seeking a resting place before a thunderstorm. The next morning it had returned to the area where it had been marked indicating that some males may fly modest distances from their home range in order to exploit a sleeping site.

DISCUSSION
To the best o our knowledge C. $implex provides the only documented example o a wasp species whose males occupy airly extensive home ranges in areas away rom an aggregation o nesting :emales. Doubtless this only reflects the lack o research o male wasps and it s probable that home ranges embracing patches o flowers are a common phenomenon n male sphecids.
The spacing system o male C. simplex does, however, differ rom that oi: various close relatives, among them several species o Eucerceris as well as Philanthus and Clypeadon (Alcock,975 and in prep.). Males o these related species orm relatively dense aggregations with each individual applying an attractant pheromone rom abdominal glands to a perch and vigorously repelling all intruders rom an area roughlyrn in radius around the perch. Whether all the members o one genus share the same basic mating strategy is unknown and will require much urther study, 'although the very limited current information hints that this may be the case (Alcock, in prep.).
Despite the differences between C. simplex and other philanthinine wasps there are some similarities as well. In all cases males occupy a perch to which they return ater bouts o flying around. All pursue a remarkably wide range o flying insects evidently in an effort to determine the species and sex o the passerby or intruder. The key variable between different species is the area inspected by an individual. Those males that use a perch as a calling post deend it and a small area around it while C. simplex, which does not appear to employ an attractant pheromone, covers a much larger area (up to at least 40 m), so large as to be essentially indefensible. Attempts to drive all other males rom a strip o roadside ditch 5 rn X 2 rn would require an extraordinary investment in aggressive territorial patrolling. Instead, C. simplex males make no special effort to locate and repel conspeciic males. Time and energy are devoted to repeated investigation o a large area in a location likely to attract ]emales, one which is rich in nectar-producing flowers or beetleproducing bushes. Having ound a potentially good area, males remain there becoming amiliar with its prime spots. Presumably this is a superior strategy than one that would take a male on a random journey through the countryside in search o a mate. Because naturally occurring attractants (,e.g. flowers) that draw in emales tend to be patchily distributed, one would predict that males o other species that use such attractants to ocus their search or emales will 1974] Alcock & Gamboa--Cerceris 533 also possess home ranges. Additional comparative data based on studies of marked populations of males are required to test this prediction.